1. Technical Field
The disclosed technology relates to electronic systems, and in particular, to power amplifiers and other amplification circuits for radio frequency (RF) electronics.
2. Description of the Related Technology
Power amplifiers boost the power of a radio frequency (RF) signal having a relatively low power. Thereafter, the boosted RF signal can be used for a variety of purposes, such as driving the antenna of a transmitter.
Power amplifiers can be included in a variety of electronic devices, such as mobile phones, to amplify a RF signal for transmission. For example, in mobile phones having a time division multiple access (TDMA) architecture, such as those found in Global System for Mobile Communications (GSM), code division multiple access (CDMA), and wideband code division multiple access (W-CDMA) systems, a power amplifier can be used to amplify a RF signal. It can be important manage the amplification of a RF signal, as a particular mobile phone can be assigned a transmission time slot for a particular frequency channel. Power amplifiers can be employed to prevent signal degradation through amplification. Power amplifiers may also operate at different modes of operation (e.g., a high power mode and a low power mode), which may produce RF output signals having different ranges of power. In certain applications, such as mobile phones, different modes of operation may be designed to reduce power consumption and increase efficiency while maintaining signal quality.
However, it can be difficult to design a power amplifier to operate at more than one mode of operation without degrading performance in the various modes of operation. Accordingly, there is a need for improved power amplifiers. Furthermore, there is a need for improved apparatus and methods for controlling and/or biasing power amplifiers at multiple power modes of operation.
In addition, electronic systems may disable at least a portion of the system when the portion is unused, for example, during an idle, energy conserving mode. An enable circuit can enable and/or refresh a voltage supply from a voltage source (e.g., a battery) to at least a portion of the electronic system. In a specific example, a mobile phone that includes a power amplifier can disable at least a portion of the power amplifier using the enable circuit when the portion of the power amplifier is not in operation. However, in this example, the power amplifier may still include a physical connection to a voltage source in through the enable circuit. As a result, leakage current may still be consumed in the idle mode. This leakage can lead to additional power consumption and/or a reduced battery life. Accordingly, a need exists for reducing the leakage current.